The present invention relates to a cigarette filling optical control method.
More specifically, the present invention relates to a method of controlling the conformation of the open end of cigarettes and, in particular, the presence or absence of tobacco at the open end, on a cigarette manufacturing machine and/or filter assembly machine and/or packing machine.
At the output of a cigarette manufacturing machine and/or filter assembly machine and/or at the input of a packing machine, the cigarettes are normally subjected to numerous checks comprising a check of the filling to determine the presence or absence of tobacco at the open end of the cigarettes.
In most cases, filling control consists in illuminating the front surface of the open end of the cigarette by means of a light source; forming an image of the front surface by means of a detecting unit featuring a telecamera or equivalent optical monitoring system; and transmitting the image to a comparing unit for comparing it with a specimen image and emitting a reject signal in the event the detected and specimen images differ over and above a given limit.
In general, the difference in the detected and specimen images depends on differences in shading which, as is known, varies according to the presence of gaps on the front surface due to the absence of tobacco. Unfortunately, the shading of the detected image has been found to depend largely, not only on the presence of gaps, but also on the color of the tobacco employed, so that known devices of the above type involve expensive, time-consuming setup procedures whenever the type of tobacco is changed.